LARGO — About 30 people rallied in front of the West Bay Surgery Center Thursday afternoon in support of the embattled Affordable Care Act, the controversial health care measure, commonly referred to as Obamacare.

Organizers say the effort was an attempt to counter what they say is widespread misinformation about the law, which has been a source of deep contention since before its passage in 2010. Similar rallies are going on across the country, led by supporters and those who want the law repealed, and passion on either side is intensifying.

Staunch opposition to the law is at the heart of the ongoing government shutdown that has temporarily closed museums, national parks and furloughed federal employees. Health care reform advocates hope they can convince others of its purported benefits.

“We are just trying to make sure we have an opportunity to counteract some of the myths that are out there, the very dangerous myths,” said Susan Lylis, a volunteer with Organizing for America, the group behind the event.

Thursday’s rally was planned before efforts in the House of Representatives to defund the Affordable Care Act led to the Oct. 1 shutdown, Lylis said. The Washington-based group has been organizing rallies across the country.

Retired Tampa physician Joel Fyvolent said he came out because he thinks the law, while not perfect, is a start.

“I’m a strong believer that the Affordable Health Care Act is a good thing for the country, a good thing for Florida,” he said. “It’s not perfect, needs to be tweaked.”

Thursday’s demonstration followed last week’s League of Women Voters rally in support of the law in downtown St. Petersburg. Saturday, members of the nonprofit Doctors for America will be participating in the Rotary Club 5k run around The Pier in an attempt to spark conversation about health care.

Members of Tea Party groups had been organizing protests against the Affordable Care Act throughout the country in the months leading up to last week’s unveiling of new health care exchanges, a key piece of the law.

Whether either side will be effective in changing minds is hard to say, and polls generally show Americans are somewhat split on the issue.

In Largo, opinions of passing drivers were also mixed. Numerous drivers honked their horns or gave a thumbs-up in support of Thursday’s demonstrators, but a handful of vocal opponents also expressed their dislike of the policy, often with obscene shouts or hand gestures.